Medication delivery device

ABSTRACT

A medication delivery device is provided which is switchable between an operational state and a resetting state and which comprises a housing having a proximal end and a distal end, a piston rod being moveable in a distal direction with respect to the housing for medication delivery, a conversion element adapted to at least partially convert a rotational movement of the piston rod into an axial movement of the piston rod, coupling means prevented from rotational movement with respect to the housing and adapted to engage with the conversion element in the operational state, a drive assembly comprising at least two drive assembly members and adapted for moving the piston rod in the distal direction, and a resilient member adapted to provide a force on the drive assembly for engagement of the drive assembly members. In the operational state of the device the coupling means is engaged with the conversion element, the conversion element thereby being prevented from rotation with respect to the housing. In the resetting state of the device the coupling means is disengaged from the conversion element under force of the resilient member, the conversion element thereby being allowed to rotate with respect to the housing and thereby allowing a resetting of the device.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. patent applicationSer. No. 13/701,987, filed Dec. 4, 2012, entitled “Medication DeliveryDevice,” which is a U.S. National Phase Application pursuant to 35U.S.C. § 371 of International Application No. PCT/EP2011/059565 filedJun. 9, 2011, which claims priority to European Patent Application No.10165637.9 filed on Jun. 11, 2010. The entire disclosure contents ofthese applications are herewith incorporated by reference into thepresent application.

FIELD OF INVENTION

The present invention relates to a medication delivery device fordelivering a dose of a medication, for example to a reusable pen-typeinjection device. The device may be configured to dispense variabledoses of the medication where a user can vary the size of a dose.Alternatively, the device may be a fixed dose device, in particular adevice configured to dispense doses of the drug which may not be variedby the user. The drug delivery device may be a manually, in particular anon-electrically driven device.

BACKGROUND

In particular, the present invention may relate to such medicationdelivery devices where a user may set a dose of medication to bedelivered from a multi-dose cartridge. Most preferably, the medicationdelivery device comprises a single- or multi-dose medication cartridgewhich can be replaced when the medication for example has been fullydispensed or has passed its date of expiry.

Medication delivery devices of the kind mentioned above have becomewidespread where regular injections by persons without formal medicaltraining occur. This is increasingly common among those having diabeteswhere self-treatment enables such persons to conduct effectivemanagement of their diabetes.

As a result of environmental and economical reasons, medication deliverydevices of the type mentioned above have been developed to allow only apart of the device to be discarded, usually the medication cartridgeonly, and the other part to be reused. This provides the additionalrequirement for such a medication delivery device that the resetting ofa drive mechanism, when a new cartridge is attached to or inserted intothe medication delivery device, needs to be easy and unambiguous,thereby reducing the possibility of damage to the drive assembly.

SUMMARY

It is an object of the present invention to disclose a medicationdelivery device comprising a reset mechanism which facilitates aresetting of the medication delivery device and which nevertheless iscost-effective.

This object is achieved with the medication delivery device according toclaim 1. Further aspects and variations of the invention derive from thedepending claims.

The medication delivery device is switchable between an operationalstate and a resetting state and comprises:

a housing having a proximal end and a distal end,

a piston rod being moveable in a distal direction with respect to thehousing for medication delivery,

a conversion element adapted to at least partially convert a rotationalmovement of the piston rod into an axial movement of the piston rod,

a coupling means prevented from rotational movement with respect to thehousing and adapted to engage with the conversion element in theoperational state,

a drive assembly comprising at least two drive assembly members andadapted for moving the piston rod in the distal direction,

a resilient member adapted to provide a force on the drive assembly forengagement of the drive assembly members, wherein

in the operational state of the device the coupling means is engagedwith the conversion element, the conversion element thereby beingprevented from rotation with respect to the housing, and

in the resetting state of the device the coupling means is disengagedfrom the conversion element on the force of the resilient member, theconversion element thereby being allowed to rotate with respect to thehousing and thereby allowing a resetting of the device.

Such a medication delivery device may have the advantage that theresilient member fulfils double functionalities.

In a first aspect, the resilient member provides a force on the driveassembly for engagement of the drive assembly members. This may enablethe drive assembly members to interact with each other for moving thepiston rod in the distal direction during medication delivery. In asecond aspect the resilient member may provide a force such that thecoupling means becomes disengaged from the conversion element duringswitching of the device from the operational state into the resettingstate. In the resetting state, the conversion element may be allowed tofreely rotate with respect to the housing. According to this concept,the medication delivery device is resettable in the resetting state bymoving the piston rod in the proximal direction into the housing andthereby rotating the conversion element. This may provide for a smoothand easy reset action and may aid all users, but particularly those withimpaired dexterity. Furthermore the device may be cost-effective withthe resilient member fulfilling double duties because no additionalcomponent is needed.

The term “housing” shall preferably mean any exterior housing (“mainhousing”, “body”, “shell”) or interior housing (“insert”, “inner body”).The housing may be designed to enable the safe, correct, and comfortablehandling of the medication delivery device or any of its mechanism.

The term “conversion element” shall preferably mean any componentdesigned to guide the piston rod in the operational state duringmedication delivery, thereby converting rotational movement of thepiston rod into axial movement of the piston rod, preferably in distaldirection with respect to the housing. For this purpose the conversionelement preferably comprises a shape for interacting with acorresponding shape of the piston rod. For example, the conversionelement may be a kind of nut element and the piston rod may be a kind oflead screw. Furthermore, when the conversion element and therefore themedication delivery device are in the operational state, the conversionelement may be designed to prevent the resetting of the medicationdelivery device, i.e. it directly or indirectly prevents a movement ofthe piston rod in the proximal direction. Additionally, when theconversion element and therefore the medication delivery device are inthe resetting state, the conversion element may be designed to enablethe resetting of the medication delivery device, i.e. it directly orindirectly allows a movement of the piston rod in the proximaldirection. Hence, the medication delivery device is switchable betweenthe operational state and the resetting state, the conversion elementassuming the respective state.

The term “drive assembly” shall preferably mean any assembly in which afirst drive assembly member is configured to transfer force, preferablytorque, to a second drive assembly member. The transferred force maycause the second drive assembly member to be axially displaced withrespect to the housing for dose delivery. Preferably, the drive assemblymay drive a piston rod for delivery of a medication.

The term “operational state” according to the present invention shallpreferably mean a state of the device, where a dispensing of medicationis enabled. Moreover, it preferably means a position of the conversionelement in which the conversion element prevents the resetting of themedication delivery device. Preferably, the operational state isfurthermore a position or state of the conversion element in which theconversion element guides and/or holds the piston rod. When themedication delivery device is used for dose-setting and/or medicationdelivery, the conversion element and therefore the medication deliverydevice are preferably in the operational state.

The term “resetting state” according to the present invention shallpreferably mean a state of the device, where a resetting of the drivemechanism is enabled. Moreover, it preferably means a position of theconversion element in which the conversion element allows the resettingof the medication delivery device. The conversion element is preferablyin the resetting state when the medication delivery device isdisassembled, i.e. the medication receptacle is disengaged from thehousing for replacing an old or empty cartridge with a new cartridgefilled with medication.

The term “resilient member” according to the present invention shallpreferably mean any element that is provided for exerting a force on acomponent and/or components to ensure that these components are forcedtogether, e.g. into engagement, or forced apart, e.g. out of engagement.For example, the drive assembly members are forced together by theresilient member in the operational state of the device. Besides, thecoupling means and the conversion element may be forced apart by theresilient member in the resetting state of the device. Preferably theresilient member may be manufactured from any suitable flexible energystorage material known by a person skilled in the art, e.g. metal,rubber or plastics, and may take any suitable form, e.g. a spring.

The term “coupling means” according to the present invention shallpreferably mean any component that is part of the housing, fixed to thehousing, engaged with the housing or engaged with a component fixed tothe housing such that the coupling means is prevented from rotationalmovement with respect to the housing.

The term “distal end” according to the present invention shall mean theend of the device or a component of the device which is closest to thedispensing end of the device. Preferably a needle assembly is providedat the distal end of the medication delivery device, the needle of whichcan be inserted into the skin of a patient for medication delivery.

The term “proximal end” according to the present invention shall meanthe end of the device or a component of the device which is furthestaway from the dispensing end of the device. Preferably a button or otherdosing element is provided at the proximal end of the medicationdelivery device which may be pushed for dose delivery.

The term “piston rod” according to the present invention shall mean acomponent adapted to operate through/within the housing and designed tobe moveable in axial direction (preferably towards the distal end)through/within the medication delivery device and to translate its axialmovement preferably to a piston or bung of the cartridge for the purposeof discharging/dispensing a medication from the cartridge. Said pistonrod may be flexible or not. It may be a simple rod, a lead-screw, a partof a rack and pinion system, a part of a worm gear system or the like.The piston rod shall further mean a component having a circular or anon-circular cross-section. It may be made of any suitable materialknown by a person skilled in the art.

The term “medication”, as used herein, preferably means a pharmaceuticalformulation containing at least one pharmaceutically active compound,wherein in one embodiment the pharmaceutically active compound has amolecular weight up to 1500 Da and/or is a peptide, a proteine, apolysaccharide, a vaccine, a DNA, a RNA, an enzyme, an antibody, ahormone or an oligonucleotide, or a mixture of the above-mentionedpharmaceutically active compound.

In a further embodiment the pharmaceutically active compound is usefulfor the treatment and/or prophylaxis of diabetes mellitus orcomplications associated with diabetes mellitus such as diabeticretinopathy, thromboembolism disorders such as deep vein or pulmonarythromboembolism, acute coronary syndrome (ACS), angina, myocardialinfarction, cancer, macular degeneration, inflammation, hay fever,atherosclerosis and/or rheumatoid arthritis.

In a further embodiment the pharmaceutically active compound comprisesat least one peptide for the treatment and/or prophylaxis of diabetesmellitus or complications associated with diabetes mellitus such asdiabetic retinopathy.

In a further embodiment the pharmaceutically active compound comprisesat least one human insulin or a human insulin analogue or derivative,glucagon-like peptide (GLP-1) or an analogue or derivative thereof, orexedin-3 or exedin-4 or an analogue or derivative of exedin-3 orexedin-4.

Insulin analogues are for example Gly(A21), Arg(B31), Arg(B32) humaninsulin; Lys(B3), Glu(B29) human insulin; Lys(B28), Pro(B29) humaninsulin; Asp(B28) human insulin; human insulin, wherein proline inposition B28 is replaced by Asp, Lys, Leu, Val or Ala and wherein inposition B29 Lys may be replaced by Pro; Ala(B26) human insulin;Des(B28-B30) human insulin; Des(B27) human insulin and Des(B30) humaninsulin.

Insulin derivates are for example B29-N-myristoyl-des (B30) humaninsulin; B29-N-palmitoyl-des(B30) human insulin; B29-N-myristoyl humaninsulin; B29-N-palmitoyl human insulin; B28-N-myristoyl LysB28ProB29human insulin; B28-N-palmitoyl-LysB28ProB29 human insulin;B30-N-myristoyl-ThrB29LysB30 human insulin; B30-N-palmitoyl-ThrB29LysB30human insulin; B29-N—(N-palmitoyl-Y-glutamyl)-des(B30) human insulin;B29-N—(N-lithocholyl-Y-glutamyl)-des(B30) human insulin;B29-N-(ω-carboxyheptadecanoyl)-des(B30) human insulin andB29-N-(w-carboxyheptadecanoyl) human insulin.

Exendin-4 for example means Exendin-4(1-39), a peptide of the sequenceH-His-Gly-Glu-Gly-Thr-Phe-Thr-Ser-Asp-Leu-Ser-Lys-Gln-Met-Glu-Glu-Glu-Ala-Val-Arg-Leu-Phe-Ile-Glu-Trp-Leu-Lys-Asn-Gly-Gly-Pro-Ser-Ser-Gly-Ala-Pro-Pro-Pro-Ser-NH2.

Exendin-4 derivatives are for example selected from the following listof compounds:

H-(Lys)₄-des Pro36, des Pro37 Exendin-4(1-39)-NH2,

H-(Lys)₅-des Pro36, des Pro37 Exendin-4(1-39)-NH2,

des Pro36 [Asp28] Exendin-4(1-39),

des Pro36 [IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14, Asp28] Exendin-4(1 -39),

des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(O2)25, IsoAsp28] Exendin-4(1-39); or

des Pro36 [Asp28] Exendin-4(1-39),

des Pro36 [IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14, IsoAsp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Trp(O2)25, IsoAsp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(O2)25, Asp28] Exendin-4(1-39),

des Pro36 [Met(O)14 Trp(O2)25, IsoAsp28] Exendin-4(1-39),

wherein the group -Lys6-NH2 may be bound to the C-terminus of theExendin-4 derivative;

or an Exendin-4 derivative of the sequence

H-(Lys)₆-des Pro36 [Asp28] Exendin-4(1-39)-Lys6-NH2,

des Asp28 Pro36, Pro37, Pro38Exendin-4(1-39)-NH2,

H-(Lys)₆-des Pro36, Pro38 [Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36 [Trp(O2)25, Asp28] Exendin-4(1-39)-Lys6-NH2,

H-des Asp28 Pro36, Pro37, Pro38 [Trp(O2)25] Exendin-4(1-39)-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28]Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36 [Met(O)14, Asp28] Exendin-4(1-39)-Lys6-NH2,

des Met(O)14 Asp28 Pro36, Pro37, Pro38 Exendin-4(1-39)-NH2,

H-(Lys)6-desPro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)₅-des Pro36, Pro37, Pro38 [Met(O)14, Asp28]Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-Asn-(Glu)5 des Pro36, Pro37, Pro38 [Met(O)14, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-Lys6-des Pro36 [Met(O)14, Trp(O2)25, Asp28] Exendin-4(1-39)-Lys6-NH2,

H-des Asp28 Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25]Exendin-4(1-39)-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Asp28] Exendin-4(1-39)-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(1-39)-NH2,

des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2,

H-(Lys)6-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)₂₅, Asp28]Exendin-4(S1-39)-(Lys)6-NH2,

H-Asn-(Glu)5-des Pro36, Pro37, Pro38 [Met(O)14, Trp(O2)25, Asp28]Exendin-4(1-39)-(Lys)6-NH2;

or a pharmaceutically acceptable salt or solvate of any one of theafore-mentioned Exedin-4 derivative.

Hormones are for example hypophysis hormones or hypothalamus hormones orregulatory active peptides and their antagonists as listed in RoteListe, ed. 2008, Chapter 50, such as Gonadotropine (Follitropin,Lutropin, Choriongonadotropin, Menotropin), Somatropine (Somatropin),Desmopressin, Terlipressin, Gonadorelin, Triptorelin, Leuprorelin,Buserelin, Nafarelin, Goserelin.

A polysaccharide is for example a glucosaminoglycane, a hyaluronic acid,a heparin, a low molecular weight heparin or an ultra low molecularweight heparin or a derivative thereof, or a sulphated, e.g. apoly-sulphated form of the above-mentioned polysaccharides, and/or apharmaceutically acceptable salt thereof. An example of apharmaceutically acceptable salt of a poly-sulphated low molecularweight heparin is enoxaparin sodium.

Pharmaceutically acceptable salts are for example acid addition saltsand basic salts. Acid addition salts are e.g. HCl or HBr salts. Basicsalts are e.g. salts having a cation selected from alkali or alkaline,e.g. Na+, or K+, or Ca2+, or an ammonium ion N+(R1)(R2)(R3)(R4), whereinR1 to R4 independently of each other mean: hydrogen, an optionallysubstituted C1-C6-alkyl group, an optionally substituted C2-C6-alkenylgroup, an optionally substituted C6-C10-aryl group, or an optionallysubstituted C6-C10-heteroaryl group. Further examples ofpharmaceutically acceptable salts are described in “Remington'sPharmaceutical Sciences” 17. ed. Alfonso R. Gennaro (Ed.), MarkPublishing Company, Easton, Pa., U.S.A., 1985 and in Encyclopedia ofPharmaceutical Technology.

Pharmaceutically acceptable solvates are for example hydrates.

Turning now again to the design of the medication delivery device,according to a first embodiment the conversion element is permanentlyprevented from axial movement with respect to the housing, wherebyduring switching of the device between the operational state and theresetting state the coupling means is axially moved with respect to thehousing between a first axial position according to the operationalstate of the device and a second axial position according to theresetting state of the device. Hence, the coupling means can assume twodifferent axial positions with respect to the housing according to therespective state of the device.

Preferably the medication delivery device in this first embodimentcomprises retaining means prevented from axial movement relative to thehousing, the conversion element being restrained by the retaining meansfrom moving axially. However, the conversion element is allowed torevolve with respect to the housing. The retaining means can beintegrally formed as part of the housing or as a separate member whichis secured against axial movement relative to the housing. The retainingmeans may be designed to surround and border the conversion element suchthat the conversion element is indirectly secured against axial movementrelative to the housing. Nevertheless, the retaining means preferably donot prevent the conversion element from revolving with respect to thehousing.

Preferably, according to this first embodiment, in the operational stateof the device the coupling means is held in the first axial position.Moreover, during switching of the device between the operational stateand the resetting state, the coupling means is axially moved, preferablyin distal direction, and brought into the second axial position underforce of the resilient member. During switching of the device from theoperational state into the resetting state, the force of the resilientmember urges the coupling means to disengage from the conversionelement. The conversion element and the whole device may be brought intothe resetting state, the conversion element being allowed to revolvewith respect to the housing.

According to another, second embodiment of the present invention, thecoupling means is permanently prevented from axial movement with respectto the housing, and during switching of the device between theoperational state and the resetting state the conversion element isaxially moved with respect to the housing between a first axial positionaccording to an operational state of the device and a second axialposition according to the resetting state of the device. Contrary to thefirst embodiment explained above, in this second embodiment theconversion element is axially moved during switching of the devicebetween the respective states while the coupling means is the elementwhich is permanently prevented from axial movement relative to thehousing. The coupling means can be integrally formed as part of thehousing or as separate member which is secured against axial movementwith respect to the housing.

According to this second embodiment, in the operational state of thedevice the conversion element is preferably held in the first axialposition. Moreover, during switching of the device between theoperational state and the resetting state, the conversion element isaxially moved, preferably in distal direction, and brought into thesecond axial position under force of the resilient member. Duringswitching of the device from the operational state into the resettingstate, the force of the resilient member urges the conversion element tobe disengaged from the coupling means. The conversion element and thewhole device may be brought into the resetting state, the conversionelement being free to revolve and rotate relative to the housing.

Preferably the medication delivery device comprises a medicationreceptacle adapted to be secured to the housing. The term “medicationreceptacle” in this context shall preferably mean a cartridge containinga medication or a cartridge assembly, most preferably a cartridge holderfor receiving a cartridge containing a medication. Preferably, in theoperational state of the device, the medication receptacle is secured tothe housing thereby holding the coupling means in engagement with theconversion element. In the resetting state of the device the medicationreceptacle may be removed from the housing thereby allowingdisengagement of the coupling means from the conversion element.Preferably, the device is in the operational state when the medicationreceptacle is secured to the housing and in the resetting state when themedication receptacle is removed from the housing. Switching of thewhole device between the two states is achieved by securing or removingthe medication receptacle to or from the housing. In particular, onsecuring a medication receptacle to the device, the device may beswitched from the resetting state to the operational state and byremoving the medication receptacle from the device, the device may beswitched from the operational state to the resetting state.

Furthermore, when the medication receptacle is secured to the housing,the resilient member preferably becomes strained, thereby providing aforce on the drive assembly for engagement of the drive assemblymembers. When the medication receptacle is disengaged from the housing,the resilient member preferably becomes unstrained, the drive assemblymembers of the drive assembly being allowed and enabled to be disengagedfrom each other.

The medication receptacle preferably is a cartridge holder which isprovided for receiving a cartridge filled with medication. The cartridgeholder may be designed to be engaged with a distal end of the housing ofthe device. Alternatively, the medication receptacle can be a cartridgehaving first engagement means for engaging second engagement means ofthe housing of the device. A cartridge filled with medication ispreferably a tubular sleeve containing the medication and may be closedby a piston or bung at one end and by a pierceable septum at the otherend. When the piston or bung is moved distally in the cartridge, themedication is dispensed, e.g. through a needle which pierces the septumand which is in communication with the medication.

Preferably the conversion element comprises first locking means and thecoupling means comprises second locking means, the first and secondlocking means being adapted to interlock with each other. Preferably,the first and second locking means are formed by at least one of teeth,splines, protrusions, and castellations. In the operational state, thefirst and second locking means may interlock with each other when thecoupling means and the conversion element are engaged. In the resettingstate, the first and second locking means may be disengaged when thecoupling means and the conversion element are disengaged. Byinterlocking of the first and second locking means in the operationalstate a rotational movement of the first and second locking meansrelative to each other is inhibited. Preferably the first and secondlocking means are formed such that one locking means engages in arespective negative shape of the other locking means such that theteeth, splines, protrusions and castellations of one locking means locksthe other locking means in order to prevent rotational movement withrespect to the housing.

Preferably the piston rod is threadedly engaged with the conversionelement. The conversion element thereby preferably comprises an innerthread for engaging an outer thread of the piston rod. Optionally, theconversion element comprises a circular or non-circular opening forholding the piston rod with a corresponding circular or non-circularform or a piston rod with a section having the corresponding circular ornon-circular form. Accordingly, the conversion element may act, asdescribed above, as “nut means” or a “body nut” for guiding the pistonrod and for converting a rotational movement of the piston rod into anaxial movement of the piston rod, preferably in distal direction withrespect to the housing during the operational state. In the resettingstate as mentioned above, the conversion element is free to rotate withrespect to the housing, the piston rod being allowed to be moved in theproximal direction into the housing. Thereby, the conversion element,the piston rod and in particular the threaded engagement of theconversion element and the piston rod may be designed such that aproximal movement of the piston rod results in rotational movement ofthe free-to-rotate conversion element. The thread pitch of the thread ofthe piston rod preferably is adapted such that the threaded engagementof the conversion element and the piston rod does not inhibit theconversion of proximal movement of the piston rod into rotationalmovement of the conversion element. Thus, the threaded engagement of theconversion element and the piston rod acts as a non-self-lockingengagement at least in the resetting state of the device.

Preferably the medication delivery device comprises a drive member whichis a first drive assembly member of the drive assembly and which isadapted to be rotated with respect to the housing, wherein rotationalmovement of the drive member with respect to the housing is convertedinto movement of the piston rod in the distal direction with respect tothe housing. Preferably, the drive member is at least in the operationalstate engaged with the piston rod such that rotational movement of thedrive member results in a rotational movement of the piston rod, wherebythe conversion element, being engaged with the piston rod, urges thepiston rod into a helical movement such that a rotational movement ofthe piston rod is at least partially converted into movement of thepiston rod in the distal direction with respect to the housing.

However, in the resetting state the piston rod can be axially moved inproximal direction into the housing, the conversion element therebyfreely rotating.

If during proximal movement the piston rod does not rotate with respectto the housing, movement of the piston rod may be not converted intorotational movement of the drive member such that the drive member doesnot rotate. But if during proximal movement the piston rod does rotatewith respect to the housing, movement of the piston rod may be convertedinto rotational movement of the drive member as the drive member is heldin engagement with the piston rod. Thus, in the case that the piston rodrotates during resetting, the drive member may have to be separated anddisengaged from other drive assembly members, for example via aseparation mechanism of the drive assembly, in order that the drivemember can follow rotational movement of the piston rod without beinginhibited in rotational movement by other drive assembly members.

Preferably the medication delivery device comprises a rotation memberwhich is a second drive assembly member of the drive assembly and whichis adapted to be rotated in a first direction with respect to thehousing during setting of a dose of a medication and to be rotated in asecond direction with respect to the housing during delivery of thedose, the second direction being opposite to the first direction.Preferably in the operational state the drive member is adapted tofollow rotational movement of the rotation member in the seconddirection with respect to the housing during delivery of the dose. It ispreferred, that the drive member and the rotation member are engaged orheld in abutment by the force provided by the resilient member duringsetting and delivery of the dose in the operational state. Preferably,during setting of a dose in the operational state, the rotation memberis rotated in the first direction, whereby rotational movement of thedrive member can be avoided.

During delivery of the dose in the operational state a rotationalmovement of the rotation member in the second direction may betransmitted into rotational movement of the drive member in the seconddirection. That may cause the piston rod to start the helical movementof the kind mentioned above, whereby the piston rod traverses thehousing of the device in distal direction and pushes a piston or bung ofthe cartridge in distal direction thereby expelling a predeterminedamount, i.e. a dose, of the medication out of a needle at the distal endof the device.

Preferably the drive member and the rotation member are coupled to oneanother by a first uni-directional friction clutch mechanism which isconfigured to permit rotational movement between the drive member andthe rotation member during rotation of the rotation member in the firstdirection for setting of the dose and to prevent relative rotationalmovement of drive member and rotation member during rotational movementof the rotation member in the second direction for delivery of the dose.

Preferably the drive assembly is designed such that the drive member isengaged with a stop member which is as a third drive assembly member ofthe drive assembly and which is adapted to prevent rotational movementof the drive member in the first direction with respect to the housingand to permit rotational movement of the drive member in the seconddirection with respect to the housing. That means, during setting of thedose of medication and rotating the rotation member in the firstdirection, the drive member is prevented from rotational movement whichresults in preventing a helical movement of the piston rod in proximaldirection and thus prevents inaccuracy of a preset dose. However, duringdelivery of the dose rotational movement of the rotation member istransmitted into rotational movement of the drive member such that thepiston rod is moved in distal direction for expelling a medication outof the device.

Preferably the drive member and the stop member are coupled to oneanother by a second uni-directional friction clutch mechanism, which isconfigured to prevent relative rotational movement between the drivemember and the stop member in the first direction with respect to thehousing and to permit relative rotational movement between the drivemember and the stop member in the second direction with respect to thehousing.

Further features, refinements and expediencies become apparent from thefollowing description of the exemplary embodiments in connection withthe figures.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 schematically shows a partly sectional side view of an exemplaryembodiment of a medication delivery device.

FIG. 2 schematically shows a perspective sectional view of a part of adrive assembly with schematically indicated movements of elementsthereof during setting of a dose.

FIG. 3 schematically shows a more detailed side view of a part of FIG.2.

FIG. 4 schematically shows a perspective sectional view of a firstembodiment of the reset mechanism in exploded view of the components.

FIG. 5 schematically shows a more detailed perspective sectional view ofa part of FIG. 4.

FIG. 6 shows a sectional view of the embodiment according to FIG. 4 inthe operational state.

FIG. 7 schematically shows a perspective sectional view of theembodiment according to FIG. 4 in the resetting state.

FIG. 8 schematically shows a perspective sectional view of a secondembodiment of the reset mechanism in exploded view of the components.

FIG. 9 schematically shows a more detailed perspective sectional view ofa part of FIG. 8.

FIG. 10 shows a sectional view of the embodiment according to FIG. 8 inthe operational state.

FIG. 11 schematically shows a perspective sectional view of theembodiment according to FIG. 8 in the resetting state.

FIG. 12 schematically shows a more detailed perspective sectional viewof a part of FIG. 11.

DETAILED DESCRIPTION

Turning now to FIG. 1, a medication delivery device 1 comprises amedication receptacle 2 and a drive assembly 3. The medicationreceptacle 2 comprises a cartridge 4. Medication 5 is retained in thecartridge 4. The medication 5 is preferably liquid medication. Thecartridge 4 preferably comprises a plurality of doses of the medication5. The medication 5 may comprise for example insulin, heparin, growthhormones or any other composition of the type named above. The cartridge4 has an outlet 6 at its distal end. Medication 5 can be dispensed fromthe cartridge through outlet 6. The device 1 may be a pen-type device,in particular a pen-type injector. The device 1 may be a disposable or areusable device. The device 1 may be a device configured to dispensefixed doses of the medication or variable, preferably user-settable,doses. The device 1 may be a needle-based or a needle free device. Thedevice 1 may be an injection device.

In FIG. 1, the distal end of the device 1 was assigned reference numeral7 and the proximal end of the device was assigned reference numeral 8.

The outlet 6 may be covered by a membrane 9, which protects medication 5against external influences during storage of the cartridge. Formedication delivery, membrane 9 may be opened, e.g. pierced. Forexample, membrane 9 may be pierced by a needle unit (not explicitlyshown). The needle unit may be (releasably) attached to the distal endof the medication receptacle 2. The needle unit may provide for fluidcommunication from the inside of the cartridge 4 to the outside of thecartridge through outlet 6.

A piston 10 is retained within the cartridge 4. The piston 10 is movablewith respect to the cartridge. The piston 10 may seal the medication 5within the cartridge. The piston 10 expediently seals the interior ofthe cartridge 4 proximally. Movement of the piston 10 with respect tothe cartridge 4 in the distal direction causes medication 5 to bedispensed from the cartridge through outlet 6 during operation of thedevice.

The medication receptacle 2 furthermore comprises a cartridge retainingmember 11. The cartridge 4 is retained within the cartridge retainingmember 11. The cartridge retaining member 11 may stabilize the cartridge4 mechanically. Additionally or alternatively, the cartridge retainingmember 11 may be provided with a fixing member (not explicitly shown)for attaching the medication receptacle 2 to the drive assembly 3.

The medication receptacle 2 and the drive assembly 3 are secured to oneanother, preferably releasably secured. A medication receptacle 2 whichis releasably secured to the drive assembly may be detached from thedrive assembly 3, for example in order to allow for providing for a newcartridge 4, if all of the doses of medication which once were in thecartridge formerly attached to the drive assembly 3 have already beendispensed. The cartridge retaining member 11 may be releasably securedto the drive assembly 3 via a thread, for example.

Alternatively, the cartridge retaining member 11 may be dispensed with.It is particularly expedient, in this case, to apply a robust cartridge4 and to attach the cartridge directly to the drive assembly 3.

The drive assembly 3 is configured for transferring force, preferablyuser-exerted force, particularly preferably manually exerted force, tothe piston 10 for displacing the piston 10 with respect to the cartridge4 in the distal direction. A dose of medication may be dispensed fromthe cartridge in this way. The size of the delivered dose may bedetermined by the distance by which the piston 10 is displaced withrespect to the cartridge 4 in the distal direction.

Furthermore, the drive assembly comprises a piston rod 12. The pistonrod 12 may be configured for transferring force to the piston 10,thereby displacing the piston 10 in the distal direction with respect tothe cartridge 4. A distal end face of the piston rod 12 may be arrangedto abut a proximal end face of the piston 10. A bearing member (notexplicitly shown) may be arranged to advance the piston 10, preferablyto abut the proximal end face of the piston 10. The bearing member maybe arranged between piston 10 and piston rod 12. The bearing member maybe fixed to the piston rod 12 or a separate member. If the piston rod 12is configured to be rotated during operation of the device, for exampleduring dose delivery, it is particularly expedient to provide for abearing member. The bearing member may be displaced together with the(rotating) piston rod 12 with respect to the housing. The piston rod 12may be rotatable with respect to the bearing member. In this way, therisk that the rotating piston rod 12 drills into the piston and therebydamages the piston is reduced. Accordingly, while the piston rod 12rotates and is displaced with respect to the housing, the bearing memberis preferably only displaced, i.e. does not rotate. The piston rod 12may be bounded by the bearing member.

The drive assembly 3 comprises a housing 13 which the piston rod 12 maybe retained in. A proximal end side 14 of the medication receptacle 2may be secured to the drive assembly 3 at a distal end side 15 of thehousing 13, for example via a threaded connection. Housing 13, cartridge4 and/or cartridge retaining member 11 may have a tubular shape.

The drive assembly 3 comprises a dose part 16. The dose part 16 ismovable with respect to the housing 13. The dose part 16 may be movablein the proximal direction with respect to the housing for setting of adose of the medication 5 which is to be delivered and in the distaldirection with respect to the housing for delivery of the set dose. Thedose part 16 is preferably connected to the housing 13. The dose part 16may be secured against rotational movement with respect to the housing.The dose part 16 may be moved (displaced) between a proximal endposition and a distal end position with respect to the housing 13 (notexplicitly shown). The distance by which the dose part is displaced withrespect to the housing during setting of the dose may determine a sizeof the dose. The proximal end position and the distal end position maybe determined by a respective stop feature which may limit the proximalor distal travel of the dose member with respect to the housing. Thedevice 1 may be a variable dose device, i.e. a device configured fordelivering doses of medication of different, preferably user-settable,sizes. Alternatively, the device may be a fixed dose device.

The device 1 may be a manually, in particular non-electrically, drivendevice. The (user-applied) force which causes the dose part 16 to bemoved with respect to the housing 13 in the distal direction may betransferred to the piston rod 12 by the drive assembly 3. For thispurpose, drive assembly members may be provided which are not explicitlyshown in FIG. 1. The drive assembly 3 is preferably configured to notmove the piston rod 12 with respect to the housing 13 when the dose partis moved in the proximal direction with respect to the housing forsetting of the dose.

An embodiment of a drive assembly 3 which is suitable for beingimplemented in the medication delivery device 1 as described above isdescribed in connection with FIGS. 2 and 3.

The drive assembly 3 comprises a housing part 17. The housing part 17has a proximal end 18 and a distal end 19. The housing part 17 may be(outer) housing 13 of FIG. 1, a part thereof or an insert within housing13, the insert being preferably secured against rotational and axialmovement with respect to housing 13. The housing part 17 may be aninsert sleeve, for example. The insert sleeve may be snap-fitted orglued to housing 13, for example. The housing part 17 may have a tubularshape. Housing part 17 may comprise outer fixing elements (not shown),for example snap-fit elements, for fixing housing part 17 to housing 13.

The piston rod 12 is retained in the housing 13, preferably withinhousing part 17. The piston rod 12 is driven in the distal directionwith respect to the housing part 17 during dose delivery.

The drive assembly furthermore comprises a drive member 20 which is afirst drive assembly member of the drive assembly 3. Drive member 20 isretained within the housing part 17. Drive member 20 is configured totransfer force, preferably torque, to the piston rod 12. The transferredforce may cause the piston rod 12 to be displaced in the distaldirection with respect to the housing part 17 for dose delivery.

Drive member 20 is rotatable with respect to housing part 17. The drivemember 20 may engage the piston rod 12. Rotational movement of the drivemember 20, for example rotational movement in a second direction may beconverted into distal movement of the piston rod 12 with respect to thehousing part 17. This is explained in more detail below.

The drive assembly furthermore comprises a rotation member 21 which is asecond drive assembly member of the drive assembly 3. The rotationmember 21 is rotatable with respect to the housing part 17 in a firstdirection, in particular for setting of a dose of the medication, and ina second direction, in particular for delivering the set dose. Thesecond direction is opposite to the first direction. According to FIGS.2 and 3, the first direction may be counter-clockwise and the seconddirection may be clockwise as seen from the proximal end of the device,for example.

Drive member 20, rotation member 21 and/or piston rod 12 are preferablyconfigured to be rotatable about a (common) rotation axis. The rotationaxis may extend through drive member 20, rotation member 21 and/orpiston rod 12. The rotation axis may be the main longitudinal axis ofthe piston rod 12. The rotation axis may run between the proximal endand the distal end of the housing part 17.

The rotation member 21 is coupled to the drive member 20 by auni-directional clutch mechanism, in particular a friction clutchmechanism. This clutch mechanism permits rotational movement of therotation member 21 with respect to the drive member 20 when the rotationmember 21 rotates in the first direction with respect to the housingpart 17. The clutch mechanism prevents rotational movement of therotation member 21 with respect to the drive member 20, when therotation member 21 rotates in the second direction with respect to thehousing part 17. The drive member 20 may thus follow rotational movementof the rotation member 21 in the second direction with respect to thehousing part 17.

The drive member 20 is arranged to abut and/or engage the rotationmember 21 and, in particular, engages rotation member 21. The drivemember 20 comprises a toothing 22 at one end, e.g. its proximal end. Therotation member 21 comprises a toothing 23 at one end which end facesthe drive member 20, e.g. its distal end. Toothing 22 comprises aplurality of teeth 24. Toothing 23 comprises a plurality of teeth 25.Teeth 24 and/or 25 may extend along the rotation axis. Toothings 22 and23 may be configured to mate with one another.

The teeth 24 may be circumferentially disposed on the drive member 20,particularly at the end of the drive member 20 which faces the rotationmember 21. The teeth 25 may be circumferentially disposed on therotation member 21, particularly at the end of the rotation member 21which faces the drive member 20.

When the steep end faces of two teeth abut and the rotation member 21 isrotated further on in the second direction, the steep sides stay inabutment and drive member 20 follows the rotation of rotation member 21.When the rotation member 21 rotates in the first direction, the ramp ofthe teeth—which ramps, in particular, run obliquely with respect to therotation axis—slide along each other and, inconsequence, the rotationmember 21 may rotate with respect to the drive member 20.

The drive assembly 3 furthermore comprises a stop member 26 which is athird drive assembly member of the drive assembly 3. The drive member 20may be arranged between the stop member 26 and the rotation member 21.The stop member 26 is configured for preventing rotational movement ofthe drive member 20 in the first direction with respect to the housingpart 17 during setting of a dose, i.e. when the rotation member 21rotates in the first direction. Thus, the rotation member 21 may rotatein the first direction with respect to the housing part 17, whereas thedrive member 20 and the stop member 26 do not rotate.

The stop member 26 is coupled to the drive member 20 by anotheruni-directional clutch mechanism, in particular a friction clutchmechanism. This clutch mechanism prevents rotational movement of thedrive member 20 with respect to the stop member 26 when the rotationmember 21 rotates in the first direction with respect to the housingpart 17. The clutch mechanism permits rotational movement of the drivemember 20 with respect to the stop member 26, when the rotation member21 rotates in the second direction with respect to the housing part 17.

Thus, the rotation member 21 may rotate with respect to the drive member20 and the stop member 26 in the first direction during setting of thedose, with rotation of the drive member 20 being prevented by itsinteraction with the stop member 26, and rotation member 21 as well asdrive member 20 may rotate with respect to the stop member 26 in thesecond direction during delivery of the dose.

The stop member 26 may be arranged to abut and/or engage the drivemember 20 during setting of the dose and, preferably, during delivery ofthe dose. The stop member 26 has a toothing 27 at one end which facesthe drive member 20, e.g. its proximal end. The teeth may be ramp-shapedwith a steep side and a less steep ramp. The teeth may be azimuthallydisposed along the stop member 26, in particular on the perimeter of thestop member 26.

Drive member 20 has a toothing 28 at one end which faces the stop member26, e.g. its distal end. Toothings 22 and 28 of the drive member 20 areoppositely disposed. Toothing 28 may be configured in accordance withtoothing 23 of the rotation member 21. Toothing 22 may be configured inaccordance with toothing 27 of the stop member 26. Toothings 27 and 28,in particular the steep sides of the teeth, do cooperate, e.g. abut, forpreventing rotation of the drive member 20 with respect to the housingpart 17 and, in particular, with respect to the stop member 26 in thefirst direction.

Stop member 26 is preferably secured against rotational movement withrespect to the housing part 17. Stop member 26 may be fixed to thehousing or integrated into the housing. Stop member 26 may be fixedagainst displacement with respect to the housing part 17 or displacementwith respect to the housing part 17 may be allowed.

As it is illustrated in the present embodiment, stop member 26 isdisplaceable with respect to the housing but non-rotatable with respectto the housing part 17. For that purpose, one or a plurality of,preferably oppositely disposed, guide features, for example guide lugs29, are provided in the stop member 26. The respective guide feature 29engages a corresponding guide slot 30 which may be provided in thehousing, e.g. in housing part 17. This can be seen in FIGS. 2 and 3. Aguide feature 29 cooperates with a guide slot 30 to prevent rotationalmovement of the stop member 26 with respect to the housing part 17, withaxial movement of the stop member 26 with respect to the housing beingallowed. The axial movement of the stop member 26 may compensate forplay between components of the drive assembly 3 during operation.

From the group comprising drive member 20, stop member 26 and rotationmember 21 one or more members, preferably two members or three members,may be axially displaceable (double arrow 45 in FIGS. 2 and 3) withrespect to the housing part 17 and, preferably, with respect to thepiston rod 12. Therein, the drive member 20 and another one of therecited members 21 or 26 may be axially displaceable with respect to thehousing. The remaining member may be secured against axial displacementor may also be axially displaceable during operation of the driveassembly 3 for medication delivery. Accordingly, if the drive member 20and the stop member 26 are axially displaceable, the rotation member 21may be axially secured or axially displaceable and so on. Play betweenthe components caused by relative (axial) movement of components of theclutch mechanism with respect to the housing can be compensated for inthis way. The distance by which the respective components may be axiallydisplaced with respect to the housing may correspond to the (maximum)depth of a tooth of the respective toothing 22 or 28 of the drive member20. Alternatively, the distance may be greater than the (maximum) depthof a tooth of the respective toothing.

Furthermore, the drive assembly 3 comprises a resilient member 31,preferably a spring member. The resilient member 31 may be biased duringmedication delivery operation of the drive assembly 3. The resilientmember 31 may provide for a force that tends to keep drive assemblymembers in engagement, i.e. the drive member 20 in engagement with thestop member 26 and/or the rotation member 21. The force may be exertedalong the rotation axis. In the situation shown in FIGS. 2 and 3, thisforce may be exerted in the proximal direction. The resilient member 31may be a helical (coil) spring. The resilient member 31 may be acompression spring.

The resilient member 31 may keep the drive member 20 and the stop member26 in (permanent) mechanical contact, e.g. in abutment, with each otherduring setting and delivery of a dose of the medication. Alternativelyor additionally, the resilient member 31 may keep the drive member 20and the rotation member 21 in (permanent) mechanical contact, preferablyabutment, with each other during setting and delivery of a dose of themedication.

The resilient member 31 may be integrated within stop member 26 or aseparate component. The resilient member 31 may be arranged on thedistal end side of the stop member 26.

The drive assembly 3 furthermore comprises a support member 32. Supportmember 32 is expediently fixed against axial and rotational movementwith respect to the housing part 17 or integrated into housing part 17.Support member 32 is arranged on that side of the drive member 20 whichis remote from the stop member 26. Support member 32 may be aprotrusion, for example a ring-like protrusion. Rotation member 21 mayextend through an opening in support member 32. The support member 32may provide for a counter force to the force which is exerted by theresilient member 31. Permanent abutment of the rotation member 21 withthe drive member 20 and of the drive member 20 with the stop member 26during setting and delivery of medication is facilitated in this way.

The rotation member 21 has an (radially) outwardly protruding member 33,for example a flange portion. The protruding member 33 is expedientlyprovided for abutting support member 32, in particular the distal endside of support member 32.

The drive assembly 3 furthermore comprises a dose member 34. Dose member34 may be dose part 16 or may be a part of the dose part 16 of FIG. 1.Dose member 34 is movable with respect to the housing in the proximaldirection (arrow 43) for setting of a dose and for delivery of the dose.For example, the dose member 34 may be moved in the proximal directionwith respect to the housing part 17 during dose setting and in thedistal direction with respect to the housing part 17 during dosedelivery. The dose member 34 may engage the housing part 17 or,alternatively, another part of housing 13 (not explicitly shown). Dosemember 34 is preferably secured against rotational movement with respectto the housing part 17. The dose member 34 may comprise a guide feature35, for example a guide lug or a guide slot, that engages another guidefeature, for example a guide slot or a guide lug, respectively, that isprovided in the housing part 17 or the housing 13.

Dose member 34 may be moved in the proximal direction and in the distaldirection with respect to rotation member 21. Dose member 34 is arrangedto be coupleable and is preferably (permanently) coupled to rotationmember 21 such that movement of the dose member, e.g. in the proximaldirection with respect to the housing part 17, for setting a dose of themedication is converted into rotational movement of the rotation member21 in the first direction (arrow 44) and movement of the dose member,e.g. in the distal direction with respect to the housing part 17, fordelivering the dose is converted into rotational movement of therotation member 21 in the second direction opposite to the firstdirection.

The rotation member 21 may be provided with an (outer) thread 36. Thread36 may be engaged with one of or a plurality of engagement members 49 ofdose member 34. The respective engagement member may be arranged on theinside of the dose member. The respective engagement member may be athread or a part of a thread, for example. Thus, dose member 34 androtation member 21 may be threadedly coupled, in particularly threadedlyengaged. The rotation member 21 may be arranged inside the dose member34.

The drive member 20 and the piston rod 12 are configured for rotationalmovement of the drive member 20 with respect to the housing beingconverted into rotational movement of the piston rod 12 with respect tothe housing. The drive member 20 may engage the piston rod 12. Thepiston rod 12 is displaceable with respect to the drive member 20 alonga displacement axis. Presently, the displacement axis runs along therotation axis. The drive member 20 may be splined to the piston rod 12,for example.

The piston rod 12 may be threadedly coupled to the housing 13. Thepiston rod 12 may be provided with an outer thread, for example. Thepiston rod 12 comprises an engagement track 37, preferably twooppositely disposed engagement tracks 37, on the outside. The(respective) engagement track 37 may interrupt the outer thread of thepiston rod 12. The (respective) engagement track 37 preferably extendsalong the axis along which the piston rod 12 is displaceable withrespect to the housing 13 and, in particular, with respect to the drivemember 20.

Rotational movement of the drive member 20 with respect to the housingmay thus be converted into rotational movement of the piston rod 12 withrespect to the housing and the rotational movement of the piston rod 12is, on account of the threaded engagement of the piston rod 12 and thehousing (part), converted into movement of the piston rod 12 withrespect to the housing in the distal direction.

The dose part 16 (cf. FIG. 1) may comprise a dose button 48. Dose button48 may be configured to be gripped by a user. Dose button 48 may bearranged and connected to the dose member 34 at the proximal end. Dosebutton 48 and dose member 34 may be unitary.

Turning now to FIG. 4, a first embodiment of a resettable drive assemblyof the medication delivery device 1 is shown. For setting and dispensinga dose of a medication, the resettable drive assembly comprises the samefunctional and structural features as described in FIGS. 2 and 3. InFIG. 4, further features of the drive assembly are shown which allow aresetting of the drive assembly. Essential components are depicted inexploded view. FIG. 4 shows a part of the housing 13 with the stopmember 26 and its respective toothing 27. As described in FIGS. 2 and 3,the stop member 26 interacts with the drive member 20 for driving thepiston rod 12. In FIG. 4 only the stop member 26 is depicted.Furthermore, the resilient member 31 is depicted in FIG. 4, providing aforce for engagement and abutment of stop member 26 with the respectivedrive member 20 and rotation member 21 (see FIGS. 2 and 3).

Besides the function of holding the stop member 26 in engagement withthe drive member 20, the resilient member 31 also has the function forproviding a force for disengagement of parts of the drive assembly, i.e.a conversion element 38 and coupling means 39, such that a resetting isenabled. The conversion element 38 and coupling means 39 are arranged ata distal end of the housing 13. The resilient member 31 is located suchthat it may engage with the coupling means 39 on the distal side ofresilient member 31 and may engage with the stop member 26 on theproximal side of resilient member 31.

The conversion element 38 can be surrounded and bordered by retainingmeans 40 which are integrally formed as part of the housing 13 accordingto the embodiment of FIG. 4. The retaining means 40 prevent theconversion element 38 from axial movement but permit the conversionelement 38 to rotate with respect to the housing 13. The conversionelement 38 comprises an inner thread for threaded engagement with anouter thread of the piston rod 12. Thus the conversion element 38 actsas “nut means” or “body nut” that guides and holds the piston rod 12. Inthe operational state of the device 1 when dispensing a dose, rotationalmovement of the piston rod 12 is thereby converted by the conversionelement 38 into helical movement such that the piston rod 12 is axiallymoved in distal direction through the housing 13.

Preferably, the coupling means 39 is prevented from rotational movementwith respect to the housing 13. This can be effected by engagement ofthe coupling means 39 with at least a part of the housing 13 or a partintegrally formed on the inner diameter of the housing 13 or a componentfixed to the housing 13, e.g. a spline, protrusion or a connectingelement for connecting the retaining means 40 to the housing 13. Thecoupling means 39 may engage with the at least one connecting elementsuch that rotational movement of the coupling means 39 is inhibited. Inthe operational state of the device 1 the conversion element 38interacts with the coupling means 39 such that the conversion element 38is prevented from rotational movement with respect to the housing viathe coupling means 39. For this purpose, the conversion element 38comprises a first locking means 41 and the coupling means 39 comprises asecond locking means 42.

FIG. 5 shows a detailed view of the whole resettable drive assemblycomprising the conversion element 38, coupling means 39 and theretaining means 40 arranged within the housing 13. The first and secondlocking means 41 and 42, according to this embodiment, are designed asteeth. In particular, the teeth of the first locking means 41 arecircumferentially arranged at an outer diameter of the conversionelement 38. The teeth of the second locking means 42 on the couplingmeans 39 are arranged at an inner diameter of the coupling means 39 suchthat they act as a negative form for interlocking with the teeth of thefirst locking means 41 of the conversion element 38.

According to the embodiment of FIGS. 4 and 5 the conversion element 38interacts with the retaining means 40 such that the conversion element38 is permanently secured against axial movement with respect to thehousing. The coupling means 39 is designed such that it is axiallymoveable with respect to the housing and can be brought in a firstposition according to the operational state, thereby interlocking withthe conversion element 38 and can be brought in a second positionaccording to the resetting state thereby being disengaged from theconversion element 38. The resilient member 31 provides a respectiveforce for disengaging the coupling means 39 from the conversion element38 during switching the device 1 from the operational state into theresetting state.

FIG. 6 shows a sectional side view of the components according to FIGS.4 and 5 which are assembled together. In particular, FIG. 6 shows theoperational state of the device 1, wherein the coupling means 39 islocated and held in the first position, i.e. in abutment with theconversion element 38, thereby interlocking with the conversion element38 and preventing it from rotational movement with respect to thehousing. The coupling means 39 is preferably held in this position by aproximal end side of a medication receptacle (not shown) which isinserted in and engaged with the distal end side of the housing 13, theproximal end side of the medication receptacle directly or indirectlyurging the coupling means 39 to be held in this position against theforce of the resilient member 31. Due to the engagement of the couplingmeans 39 with the conversion element 38, the conversion element 38 isprevented from rotational movement with respect to the housing 13.Furthermore, the piston rod 12 is threadedly engaged with the conversionelement 38 such that a rotational movement of the piston rod becomestransmitted into helical and thus axial movement of the piston rod 12.Due to this distal movement a piston or bung or plunger of a cartridgeof the medication receptacle (not shown) can be pushed in distaldirection for expelling medication out of the cartridge.

FIG. 6 shows the arrangement of the resilient member 31 between theconversion element 38 and the coupling means 39 being engaged to eachother on the one side and the stop member 26 on the other side. Due tothis arrangement, the resilient member 31 is enabled to fulfil doubleduties. Firstly, the resilient member 31 provides a force for engagementof the stop member 26 with the drive assembly members as explainedabove. Secondly, the resilient member 31, as it is strained in theoperational state, provides a force on the coupling means that urges thecoupling means 39 to be separated and disengaged from the conversionelement 38 during switching of the device from the operational state asdepicted in FIG. 6 into the resetting state as explained below.

This resetting state is shown in FIG. 7. A switching from theoperational state into the resetting state was initiated by removing themedication receptacle from the housing 13. The resilient member 31 urgesthe coupling means 39 to move axially away from the conversion element38, i.e. the coupling means 39 is brought from the first position into asecond position. Hence, the device has been switched from theoperational state depicted in FIG. 6 into the resetting state depictedin FIG. 7. The traverse path of the coupling means 39 is depicted byrespective arrows 46 marking the distance between the first position ofthe coupling means 39 according to FIG. 6 and the second position of thecoupling means 39 according to FIG. 7.

Thus, in the resetting state of FIG. 7, the coupling means 39 isdisengaged from the conversion element 38 thereby allowing theconversion element 38 to freely rotate with respect to the housing 13.From this it follows that the piston rod 12 can be moved in proximaldirection back into the housing 13. According to FIG. 7, the piston rodis in a position after expelling the last dose of medication and can bemoved in proximal direction back into the housing 13. The movement ofthe piston rod 12 is indicated by the arrow 45 pointing towards thedistal end of the piston rod 12. Movement of the piston rod 12 inproximal direction can e.g. be effected by a force which is exerted by ahand of a user or a new cartridge being secured to the housing 13.

The movement of the piston rod 12 results in rotational movement of theconversion element 38 which is free to rotate as described above.Preferably, the thread pitch of the piston rod 12 is to be adapted suchthat the threaded engagement of the piston rod 12 and the conversionelement 38 does not inhibit rotational movement of the conversionelement 38 during the resetting of the piston rod 12 back into thehousing 13.

In FIG. 8 another embodiment of a device 1 with a respective resettabledrive assembly 3 is depicted in exploded view of the correspondingcomponents. FIG. 8 shows parts of a device 1 according to thedescription of FIGS. 1 to 3, in particular a medication receptacle 2with a cartridge retaining member 11 which can be inserted in andengaged at its proximal end side 14 with the distal end side 15 of thehousing 13 wherein the drive members are incorporated. In particular,the housing 13 houses a drive member 20 and a stop member 26 which inthe operational state are engaged and held in engagement by a force of aresilient member 31. The functionality of the drive member 20 and thestop member 26 has been explained in connection with FIGS. 2 and 3.

Furthermore, the housing 13 houses a conversion element 38 and couplingmeans 39. According to this embodiment and contrary to the embodimentexplained in FIGS. 4 to 7, the conversion element 38 is axially moveableand can be brought and held in a first position according to anoperational state of the device and can be brought and held in a secondposition according to a resetting state of the device due to a forceprovided by the resilient member 31. The conversion element 38 comprisesan inner thread for threaded engagement with an outer thread of thepiston rod 12. In the operational state of the device, rotationalmovement of the piston rod 12 is thereby converted by the conversionelement 38 into helical movement such that the piston rod 12 is axiallymoved in distal direction through the housing 13. The coupling means 39is integrally formed as part of the housing 13 according to thisembodiment.

FIG. 9 shows a more detailed view of parts of FIG. 8, especially theconversion element 38 and the coupling means 39 interacting with eachother and being separable by the force of the resilient member 31. Theconversion element 38 comprises first locking means 41, i.e. teeth,which can be brought into engagement with second locking means 42 ofcoupling means 39, whereby the second locking means 42 acts as matchingteeth for interlocking with the first locking means 41. Acircumferential protrusion 50 integrally formed in the inner diameter ofthe housing 13 is provided for abutment of the conversion element 38 inthe second position according to the resetting state of the device afterthe conversion element 38 has been separated from the coupling means 39due to the force of the resilient member 31.

The stop member 26 can be secured against rotational movement withrespect to the housing by means of at least one protrusion 51 which isintegrally formed on the inner diameter of the housing 13 and whichinteracts with at least one negative form on the outer diameter of thestop member 26.

FIG. 10 shows the components of FIGS. 8 and 9 assembled together. Inparticular, FIG. 10 shows the operational state of the second embodimentaccording to FIGS. 8 and 9. The medication receptacle 2 with itscartridge retaining member 11 is inserted in and engaged with itsproximal end side 14 at the distal end side 15 of the housing 13,thereby pressing the conversion element 38 against the coupling means 39and holding the conversion element 38 in its position, i.e. in abutmentwith the coupling means 39. Hence, the conversion element 38 interlockswith the coupling means 39 such that the conversion element 38 issecured against rotational movement with respect to the housing. In thisoperational state the piston rod 12 which is threadedly engaged with theconversion element 38 can be moved in distal direction pushing a pistonor plunger or bung (not shown) of a cartridge within the medicationreceptacle 2 in distal direction for expelling a medication.

FIG. 10 shows the resilient member 31 being arranged between theconversion element 38 and the coupling means 39 on one side and thedrive assembly comprising stop member 26 and drive member 20 on theother side.

Furthermore, the resilient member 31 is strained due to the medicationreceptacle 2 inserted within the housing 13. In detail, the resilientmember 31 pushes the conversion element 38 in proximal direction andthus the conversion element 38 compresses the resilient member 31 whichabuts in proximal direction with the stop member 26. Accordingly, theresilient member 31, on the one hand, provides a force for holding thedrive member 20 and the stop member 26 in engagement and preferably inabutment with each other and, on the other hand, provides a force forseparating the conversion element 38 from the coupling means 39 duringthe switching of the device from the operational state according to FIG.10 into the resetting state as explained below.

In FIG. 11 the resetting state of the device is shown. Switching of thedevice 1 from the operational state according to FIG. 10 and theresetting state according to FIG. 11 was initiated with the medicationreceptacle 2 being removed from the housing 13. The resilient member 31becomes unstrained urging the conversion element 38 to be separated anddisengaged from the coupling means 39 in distal direction. Theconversion element 38 is free to rotate. Hence, the piston rod 12 can bemoved in proximal direction back into the housing 13 as indicated by thearrow 45 pointing towards the distal end of the piston rod 12. Accordingto FIG. 11 the piston rod is in a position after expelling the last doseof medication.

FIG. 12 shows a detailed view of parts of FIG. 11. Due to the force ofthe resilient member 31, on the one hand, the conversion element 38 hasbecome separated from the coupling means 39, the first locking means 41being disengaged from the second locking means 42, i.e. the respectivecircumferential teeth being separated from each other. The conversionelement 38 is brought and held in the second position according to theresetting state whereby the traverse path of the conversion elementbetween the first position and the second position is depicted by twoarrows 46 marking the distance between the first and second position.Preferably, in this resetting state the resilient member 31 provides nomore force for holding the stop member 26 and drive member 20 inengagement such that drive member 20 and stop member 26 can be separatedfrom each other, thereby bringing the drive member 20 in a position awayfrom the stop member 26. This traverse path is also depicted by secondarrows 47 marking the distance between the drive member 20 and the stopmember 26. But it is also conceivable that stop member 26 and drivemember 20 remain in engagement with each other.

In this resetting state of FIG. 12 the piston rod 12 can be moved inproximal direction back into the housing, whereby the conversion element38 is free to rotate with respect to the housing such that a resettingof the piston rod 12 is possible. Preferably, the thread pitch of thepiston rod 12 is adapted such that rotational movement of the conversionelement 38 is not inhibited. The piston rod 12 either can be exclusivelyaxially moved in proximal direction without rotation of the piston rod,the drive member 20 thereby not rotating. But it is also conceivablethat the piston rod 12 can be helically moved back into the housing 13due to the separation of the drive member 20 from the stop member 26,the drive member 20 thereby freely rotating with respect to the housing13 due to disengagement from the stop member 26.

In general, the medication delivery device with its reset mechanism asdescribed and explained above provides for a smooth and easy resetaction and aids all users, but particularly those with impaireddexterity. Furthermore, the device is cost-effective with its soleresilient member fulfilling double duties. The embodiments describedabove are exemplary and do not restrict the invention.

We claim:
 1. A medication delivery device being switchable between anoperational state and a resetting state, comprising: a housing having aproximal end and a distal end, a piston rod being moveable in a distaldirection with respect to the housing for medication delivery, aconversion element adapted to at least partially convert a rotationalmovement of the piston rod into an axial movement of the piston rod,coupling means prevented from rotational movement with respect to thehousing and adapted to engage with the conversion element in theoperational state, a drive assembly comprising at least two driveassembly members and adapted for moving the piston rod in the distaldirection, a resilient member adapted to provide a force on the driveassembly for engagement of the drive assembly members, wherein in theoperational state of the device the coupling means is engaged with theconversion element, the conversion element thereby being prevented fromrotation with respect to the housing, and in the resetting state of thedevice the coupling means is disengaged from the conversion elementunder force of the resilient member, the conversion element therebybeing allowed to rotate with respect to the housing and thereby allowinga resetting of the device.
 2. The medication delivery device accordingto claim 1, wherein the conversion element is permanently prevented fromaxial movement with respect to the housing, and during switching of thedevice between the operational state and the resetting state thecoupling means is axially moved with respect to the housing between afirst axial position according to the operational state of the deviceand a second axial position according to the resetting state of thedevice.
 3. The medication delivery device according to claim 2,comprising retaining means prevented from axial movement relative to thehousing, the conversion element being restrained by the retaining meansfrom moving axially and being allowed to revolve with respect to thehousing.
 4. The medication delivery device according to claim 2, whereinin the operational state of the device the coupling means is held in thefirst axial position, and during switching of the device between theoperational state and the resetting state the coupling means is axiallymoved and brought into the second axial position under force of theresilient member.
 5. The medication delivery device according to claim1, wherein the coupling means is permanently prevented from axialmovement with respect to the housing, and during switching of the devicebetween the operational state and the resetting state the conversionelement is axially moved with respect to the housing between a firstaxial position according to the operational state of the device and asecond axial position according to the resetting state of the device. 6.The medication delivery device according to claim 5, wherein in theoperational state of the device the conversion element is held in thefirst axial position, and during switching of the device between theoperational state and the resetting state the conversion element ismoved in distal direction and brought into the second axial positionunder force of the resilient member.
 7. The medication delivery deviceaccording to claim 1, comprising a medication receptacle adapted to besecured to the housing wherein in the operational state of the devicethe medication receptacle is secured to the housing thereby holding thecoupling means in engagement with the conversion element, and in theresetting state of the device the medication receptacle is removed fromthe housing thereby allowing disengagement of the coupling means fromthe conversion element.
 8. The medication delivery device according toclaim 1, wherein the conversion element comprises first locking meansand the coupling means comprises second locking means, the first andsecond locking means being adapted to interlock with each other.
 9. Themedication delivery device according to claim 8, wherein the first andsecond locking means are formed by at least one of teeth, splines,protrusions, and castellations.
 10. The medication delivery deviceaccording to claim 1, wherein the piston rod is threadedly engaged withthe conversion element.
 11. The medication delivery device according toclaim 1, comprising where one of the two drive assembly memberscomprises a rotation member which is adapted to be rotated in a firstdirection with respect to the housing during setting of a dose of amedication and to be rotated in a second direction with respect to thehousing during delivery of the dose, the second direction being oppositeto the first direction.
 12. The medication delivery device according toclaim 1 11, comprising where one of the two drive assembly memberscomprises a drive member which is adapted to be rotated with respect tothe housing, wherein rotational movement of the drive member withrespect to the housing is converted into movement of the piston rod inthe distal direction with respect to the housing.
 13. The medicationdelivery device according to claim 11 12, wherein in the operationalstate the drive member is adapted to follow rotational movement of therotation member in the second direction with respect to the housingduring delivery of the dose.
 14. The medication delivery deviceaccording to claim 13, wherein the drive member and the rotation memberare coupled to one another by a first uni-directional friction clutchmechanism which is configured to permit relative rotational movementbetween the drive member and the rotation member during rotation of therotation member in the first direction for setting of the dose and toprevent relative rotational movement of drive member and rotation memberduring rotation of the rotation member in the second direction fordelivery of the dose.
 15. The medication delivery device according toclaim 12, wherein the drive member is engaged with a stop member whichis adapted to prevent rotational movement of the drive member in thefirst direction with respect to the housing and to permit rotationalmovement of the drive member in the second direction with respect to thehousing.
 16. The medication delivery device according to claim 15,wherein the drive member and the stop member are coupled to one anotherby a second uni-directional friction clutch mechanism, which isconfigured to prevent relative rotational movement between the drivemember and the stop member in the first direction with respect to thehousing and to permit relative rotational movement between the drivemember and the stop member in the second direction with respect to thehousing.
 17. A medication delivery device being switchable between anoperational state and a resetting state, comprising: a housing having aproximal end and a distal end, a piston rod being moveable in a distaldirection with respect to the housing for medication delivery, a nutconfigured to cause an axial movement of the piston rod when the deviceis in the operational state, a coupling prevented from rotationalmovement with respect to the housing and configured to engage with thenut in the operational state, a drive assembly comprising at least twodrive assembly members and adapted for moving the piston rod in thedistal direction, a resilient member configured to provide an axialbiasing force on the coupling in the operational state, wherein in theoperational state the coupling is engaged with the nut, the nut therebybeing prevented from rotation with respect to the housing, and in theresetting state the coupling is disengaged from the nut under thebiasing force of the resilient member, the nut thereby being allowed torotate with respect to the housing and thereby allowing a resetting ofthe device.
 18. A medication delivery device being switchable between anoperational state and a resetting state, comprising: a housing having aproximal end and a distal end, a piston rod being moveable in a distaldirection with respect to the housing for medication delivery, a guidecomponent configured to cause an axial movement of the piston rod whenthe device is in the operational state, a coupling prevented fromrotational movement with respect to the housing and configured to engagewith the guide component in the operational state, a drive assemblycomprising at least two drive assembly members and adapted for movingthe piston rod in the distal direction, a resilient member configured toprovide an axial biasing force on the coupling in the operational state,wherein in the operational state the coupling is engaged with the guidecomponent, the guide component thereby being prevented from rotationwith respect to the housing, and in the resetting state the coupling isdisengaged from the guide component under the biasing force of theresilient member, the guide component thereby being allowed to rotatewith respect to the housing and thereby allowing a resetting of thedevice.